Make default ResponseTime the time when the Response was created.

This CL sets a default ResponseTime when a Response object is created.  This
will be overriden with the real ResponseTime when created via fetch() or Cache
API.  Synthetic Response objects created using the constructor, however, will
end up using this default value for their ResponseTime.

Bug: 747718
Change-Id: Id8c56c875d6ca00285048ebd51f92c0380dcfed1
Reviewed-on: https://chromium-review.googlesource.com/1255423Reviewed-by: Tsuyoshi Horo <horo@chromium.org>
Commit-Queue: Ben Kelly <wanderview@chromium.org>
Cr-Commit-Position: refs/heads/master@{#595665}

third_party/blink/renderer/core/fetch/fetch_response_data.cc

@@ -287,7 +287,8 @@ FetchResponseData::FetchResponseData(Type type,
     : type_(type),
       status_(status),
       status_message_(status_message),
-      header_list_(FetchHeaderList::Create()) {}
+      header_list_(FetchHeaderList::Create()),
+      response_time_(base::Time::Now()) {}
 
 void FetchResponseData::ReplaceBodyStreamBuffer(BodyStreamBuffer* buffer) {
   if (type_ == Type::kBasic || type_ == Type::kCORS) {

third_party/blink/renderer/core/fetch/fetch_response_data_test.cc

@@ -268,4 +268,9 @@ TEST_F(FetchResponseDataTest, ToWebServiceWorkerOpaqueRedirectType) {
   CheckHeaders(web_response);
 }
 
+TEST_F(FetchResponseDataTest, DefaultResponseTime) {
+  FetchResponseData* internal_response = CreateInternalResponse();
+  EXPECT_FALSE(internal_response->ResponseTime().is_null());
+}
+
 }  // namespace blink